Blood oxygen level, also know as oxygen saturation, is a percentage that represents the total amount of oxygen circulating in the blood. This amount is obtained by comparing the quantity of circulating hemoglobin that is linked to oxygen with the amount that is not linked to oxygen. Hemoglobin is a protein present on the red blood cells, which is responsible for transporting oxygen from the lungs to various parts of the body.
Ideally, blood oxygen level should be as close to 100% as possible, generally above 95%, as this indicates that there is a good amount of oxygen circulating. However, people who have chronic respiratory problems such as asthma or chronic obstructive pulmonary disease (COPD) can present with lower saturation levels (88-90%), which is an expected finding of little concern.
When an oxygen saturation level decreases very quickly or when it's under 85-90% this may be a sign of a serious health problem, such as pneumonia, heart failure, or anemia. These situations require immediate assessment and diagnosis at the hospital and require treatment as soon as possible.
How to increase blood oxygen levels
In a healthy person, when oxygen saturation is low, between 90 to 95%, it may be a sign of phlegm in the airways, which may be reducing the amount of oxygen that gets to the blood. That's why this decrease in saturation levels is common when you have flu or a cold.
Some simple measures you can try to increase blood oxygen levels immediately include:
- Coughing, to mobilize the secretions and ease oxygenation;
- Siting upright, instead of lying down, in order to reduce pressure on the lungs;
- Taking a deep slow breath, to increase the amount of air that enters the lungs;
- Go somewhere that is well ventilated, to guarantee a greater amount of oxygen;
- Avoid very hot or very cold places, as these can make breathing more difficult.
Increase O2 levels over the long-term
Some people may experience low or fluctuating oxygen levels for a more chronic period of time. This may occur with certain respiratory conditions, like chronic obstructive pulmonary disease (COPD) or emphysema. Patients with a more long-term oxygenation problem can try to increase their levels by regularly performing exercises that promote chest well expansion and more effective inhalation. Examples of such exercises include:
- Postural drainage: Lay down on your back on an inclined surface with you head lower than your body. You can do this 3 to 4 times per day for 30 seconds. This will help to mobilize secretions to make them easier to cough.
- Abdo-diaphragmatic breathing: Place a hand on your belly button and another on your chest, between your nipples. Breathe slowly through the nose, focusing on lifting the hand on your belly button and keeping the hand on your chest still. Exhale slowly through pursed lips. This will help with thoracic wall movement and with distribution of air through the chest.
- Holding your breath: Close your eyes and imagine you are rising up a building on an elevator. Inhale slowly for a second, then hold your breath when you reach the first floor. Then continue to inhale for another 2 seconds, then pause again, as you reach the second floor. Then inhale for 3 seconds, and continue this pattern until you cannot inhale any further. You can perform this 3 to 5 times per day, making sure to rest after each attempt.
- Straw breathing: You will need a cup of water and a straw for this exercise. Inhale deeply and hold for 1 second, then exhale slowly through the straw to blow bubbles into your cup of water. You can repeat this 10 times, only while sitting or standing.
Saturation that is very low, under 85%-90% this may signal a more serious health problem, such as pneumonia. Therefore, it is recommended that you go to a hospital or call for medical help to have a more detailed assessment. While you wait for medical help you can try the techniques above to increase saturation slightly and decrease respiratory effort.
It's important to remember that there are several chronic conditions that decrease saturation without indicating an emergency, which is the case of asthma, anemia, COPD, emphysema or heart problems. In these cases, it's important to speak to a doctor to understand what saturation levels may be considered normal.
Why oxygen levels are important
Oxygen saturation is considered one of the most important vital signs in a medical assessment, together with heart rate, blood pressure, respiratory rate, and body temperature. Blood oxygen level is directly linked to abnormalities or illness within the body, and a low level can be a sign of a serious health problem like:
- Breathing problems: asthma, COPD, emphysema, embolism, cystic fibrosis;
- Heart disease: heart failure, or congenital defects;
In addition to helping with reaching a diagnosis, oxygen saturation can also be used to monitor how treatment for a determined condition is going.
How COVID-19 and oxygen saturation are related
COVID-19 is an infection that mainly affects the respiratory system. It causes symptoms such as intense cough, tight chest, difficulty breathing, and fatigue. It is expected for the oxygen level to decrease slightly in people infected with COVID-19, as the lungs are not functioning normally and cannot exchange oxygen properly.
Oxygen saturation in people with COVID-19 should be maintained above 90-95%. If levels fall below this range, the patient should be assessed and the doctor may opt to start him or her on oxygen therapy in the hospital setting.
In more serious COVID-19 cases, blood oxygen levels can reach a saturation level below 80%, in which hospitalization is usually needed, generally in an ICU.
How to measure oxygen levels
Blood oxygen level can be assessed through a test called oximetry. This test can be done in two ways:
- Pulse oximeter: This is the most common and easiest way to measure oxygen saturation. It consists of a device, an oximeter, that is placed on the tip of the finger. This device will measure oxygen levels by poining a laser through the fingernail, without any type of prick or blood sample;
- Arterial blood gas: This option is less common, but it's the most precise way of knowing the exact amount of oxygen level in the blood. It requires collection of a blood sample from an artery that will be analyzed at the lab. Arterial blood gas testing also reveals other important values such as blood pH, partial pressure of oxygen (pO2) and partial pressure of carbon dioxide (pCO2).
Oximetry tests can be done at home with the use of a pulse oximeter. These can usually be purchased at a pharmacy or medical equipment store. If using one at home, ensure your fingers are relatively warm and place on a fingertip without nail polish or artificial nails, as this will guarantee a more precise result. Learn more about oximetry tests and how to measure your oxygen saturation correctly.
Normal blood oxygen levels
Normal blood oxygen levels vary according to a person's health history. For people who are generally healthy and do not have a history of chronic diseases, oxygen levels are considered normal when above 95%. It is normal to see saturation levels above 98% most of the time.
However, for people who have a history of respiratory diseases (such as COPD or asthma), oxygen saturation can vary between 88 and 95%. Blood oxygen levels below 95% should always be assessed by a doctor who can determine which range is considered to be normal. This normal range will depend on the patient's health history.